is anyone else already thinking of sanding the front for an even better bounce chance? if you had more cp I'd say try that and see if it improved the breakage.

87.5% of the dropped rounds broke. This is not bad considering the sampling size was only 8. But you want to sand the round to INCREASE the bounce chance? Maybe it is just the way you worded it. I think your idea would work, but the number of possible failures would outweigh the benefits. Especially at the cost ($1/round) of testing the breakage, as well as the flight after sanding, sanding inconsistencies, etc.

After dropping the round, was it possible to measure the shell thickness? Is the shell the same thickness in the front, as well as the back? This could give some hard #'s, without paying alot for these rounds.

yeah, the sample size is not comparable in terms of the standard test we did, but it shows that they will break under normal circumstances.

when we get more ill complete the full test for true comparison.

I've searched the forums, but couldn't find the brittleness tests you are referring to. *Edit: I passed leftystrikesback's post, and missed the google doc. Any reference to the google docs in a punkworks sticky?* Maybe I am just searching in the wrong places/words.

Anyway, aside from measuring the number of bounces out of X balls, have you tried to establish a correlation with shell thickness to your tests. I just wonder if a micrometer measurement of the thickness would provide another level of data. I know the formulation/materials of the p-balls should have some say as far as brittleness, but these are company secrets. I only ask BC those tiberius rounds are expensive, and to do a large sample might be a waste of money.

Actually I linked the google doc in my post specifically because it doesn't show up on this site as far as I know, it was linked in the description section of one of CP's youtube videos.

I don't believe that shell thickness has been measured in conjunction with a drop test. It would be easy enough to do and would tell an interesting story, however if you've never measured shell thickness before you may be in for a surprise: it is not at all constant. The shell can be almost twice as thick around the seam as it is around the poles of the ball, so when you report a thickness you need to come up with some standard for reporting. For example one person might report the thinnest part of the shell (where it might be weakest) whereas another might report the average thickness.

I have a few questions now that we can look back on this test with new knowledge.

Is the purpose of the bounce test to compare paintballs/FS at similar velocities or similar heights? Now that we know that FSR doesn't slow down as fast as paintballs, then we might want to double check what speed the FSR are hitting at 8 ft.

It really depends on how we look at it. In one sense, it could serve as a direct comparison of brittleness at the same speed. On the other hand, it could be used as a "real-world" test in that the FSR are always going to hit at a faster velocity than PB's and the drop test velocity difference is irrelevant.

From my recollection of sidebar discussions, the idea was to subject them to the same conditions as paintballs. Meaning, the same impact force. However, the impact testing occured well before the dual chrono test so nobody knew how much faster they would be going.

So, was this an accurate means to test this? This requires some thought and some math to definitively answer.

They are both subjected to the same acceleration (gravity).
They have a different drag profile but, drag is a coefficient and it gets to be a stronger 'force' the faster the projectile moves. This is what allows for 'terminal velocity' The point at which gravity's acceleration is equal and in opposition to the drag force.

The max speed any projectile can reach in 8ft is roughly 16FPS.

The question remaining is how different is the drag force at velocities less than 16FPS? My intuition tells me not very much.

Finally! this might be something I can test myself. I can do a drop test on my balcony or even in my bathroom and even better- my cellphone has a 'Highspeed' Video Capability (120Frames/Sec) maybe it will help?

From my recollection of sidebar discussions, the idea was to subject them to the same conditions as paintballs. Meaning, the same impact force. However, the impact testing occured well before the dual chrono test so nobody knew how much faster they would be going.

So, was this an accurate means to test this? This requires some thought and some math to definitively answer.

They are both subjected to the same acceleration (gravity).They have a different drag profile but, drag is a coefficient and it gets to be a stronger 'force' the faster the projectile moves. This is what allows for 'terminal velocity' The point at which gravity's acceleration is equal and in opposition to the drag force.

The max speed any projectile can reach in 8ft is roughly 16FPS.

The question remaining is how different is the drag force at velocities less than 16FPS? My intuition tells me not very much.

Finally! this might be something I can test myself. I can do a drop test on my balcony or even in my bathroom and even better- my cellphone has a 'Highspeed' Video Capability (120Frames/Sec) maybe it will help?

That sounds like a good idea. If you can, also make a grid of squares on a sheet of paper to serve as a backdrop. That way, we won't need a chrono to calculate the velocity.